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NYC/PHL: January 25-27 Potential Bomb Part 4


earthlight

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Guys, with the delayed onset, we're basically still 72 hrs out.

I wouldn't expect any consistency until tomorrow night.

None of the storms this year had any sort of lock-in until inside 48 hours.

I believe this is going to allow the new HP to build down to help feed cold air into the region, regardless of the exact track. Any thoughts on this?

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I wouldn't give an off hour NAM run any consideration whatsoever, especially since the SREFs came in significantly more amplified. Watch it come back to a roaring coastal hugger at 0z. Stranger things have happened with this model.

6/10 of the ARW/NMM 15z SREF members were well SE like the 18z NAM. So this run of the NAM doesn't surprise me very much. I also think the NAM usually leads the SREFs instead of the other way around. A few of the SREF members are also wrapped up and warm. So the operational model run could show significant jumps later today and tomorrow.

How soon the southern wave takes on a negative tilt and forces heights up along the east coast will determine how closely the low center tracks. Minor differences in this factor between 12z and 18z NAM at hrs 24-48 had huge implications on the eventual trof evolution and SLP track.

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How soon the southern wave takes on a negative tilt and forces heights up along the east coast will determine how closely the low center tracks. Minor differences in this factor between 12z and 18z NAM at hrs 24-48 had huge implications on the eventual trof evolution and SLP track.

Yup, that's the factor for the early evolution of the sfc low track. For the later evolution, it also depends on the timing of the s/w dropping into the OH Valley behind it.

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The 15z SREF is a classic example of why not to consider an ensemble mean a discrete solution. The mean shows a long duration, moderate QPF, light intensity storm, with an offshore surface track and relatively warm temps at surface and aloft. But none of the individual members come close to this representation. All are higher intensity, shorter duration, and either warmer or colder and west or east.

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Yo knock it off with that stuff, no place for it here. JM is not like that, not in the many years i have been posting on the same WX boards as him. In fact, his point about the NAM in this situation is very valid, the NAM moreso then any other model with this storm has been jumping left and right. In all honesty the NAM has not really been that great this year as a whole. Especially since this is an off hour run on the NAM it probably holds even less credence.

The Nam outside of 60 hrs is just bad in general. I would go with the remainder of the model suite for right now and look for further trends at 0z and the ensemble means. The NAM is only really useful inside of maybe 48 hours.

For my backyard, I'd be cheering on this NAM run anyway and the last couple of GFS runs, since the Euro would be a sloppy mess for me and the GGEM would be a driving soaking rain. I think in the end they will be much closer to being right than the very wobbly NAM and the very often SE biased GFS, that made a major north trend anyway from 6 to 12z today. West of 287 is where you want to be for the best chance at a major event here. Could it happen for NYC and the coast, sure, but it would be a lot harder than the NW suburbs. Hopefully, everyone from here to the NE/central PA mountains that haven't been sharing in on our fun get plastered. The Euro today was very close to such a solution-hopefully that verifies.

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Yup, that's the factor for the early evolution of the sfc low track. For the later evolution, it also depends on the timing of the s/w dropping into the OH Valley behind it.

This looks exactly right, studying the charts. If the mid-level low doesn't start to curl down along the gulf coast and pump up heights and moisture, this won't matter much though.

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The Nam outside of 60 hrs is just bad in general. I would go with the remainder of the model suite for right now and look for further trends at 0z and the ensemble means. The NAM is only really useful inside of maybe 48 hours.

For my backyard, I'd be cheering on this NAM run anyway and the last couple of GFS runs, since the Euro would be a sloppy mess for me and the GGEM would be a driving soaking rain. I think in the end they will be much closer to being right than the very wobbly NAM and the very often SE biased GFS, that made a major north trend anyway from 6 to 12z today. West of 287 is where you want to be for the best chance at a major event here. Could it happen for NYC and the coast, sure, but it would be a lot harder than the NW suburbs. Hopefully, everyone from here to the NE/central PA mountains that haven't been sharing in on our fun get plastered. The Euro today was very close to such a solution-hopefully that verifies.

Seems the sloppy mess is the most likely scenario considering the downstream setup and the fact that a high pressure area is retreating but there is no denying that the trend has been to keep the storm East and close to the BM save for the Gem and the flip-flopping SREF's which are just all over the place. Even the Euro at 12z trended east of it's 0z run. It's been the trend for two days already. As has been mentioned many times in this thread the trend has also been slower and slow enough to build in a fresh new cold air source in the form of a high pressure area in Canada and for the low to create it's own cooling. To all of the sudden think that everything is going to shift back West to prior solutions and soak us in rain (or keep us predominantly rain) really seems a reach right now, not off the table but a reach.

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Not trusting the 18Z depiction at all. Always skeptical of a tight QPF field when there are huge 850/Surface U wind anomalies.

Just my $0.02

Agreed. Great point. But the 850mb low on the 18z NAM is weak and wraps minimal warm air at this level into the cold side. Unless the NAM is exactly right about the unimpressive lower mid-levels, the QPF shield should be much more expansive.

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The position of this low at 54 hrs in the NE Gulf of Mexico is the same as it was with the December 26th storm. Hmm. I wonder if the model will have feedback problems with those thunderstorms developing down there.

There is also a 1024 high dropping down at hour 54.

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Experience tells me not to expect the precip to be offshore ... taking a wait and see approach.

Yeah. It seems like many models are deviating from a similar track once the storm hits the coast. Some take it up further, some head it OTS. For coastal locations, (and honestly even back inland), anything from several inches of snow, to rain, to flurries from a scraper is being depicted on different models. The spread is amazing for such a big storm.

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You know what? You can clearly see the difference between the GFS and the Euro by 69 hrs. The GFS is having feedback problems in the NE Gulf and is not understanding where the surface low should be. The Euro places it over Georgia and the GFS heads for Hatteras. The GFS and NAM are having feedback issues here that the Euro is not having. The GFS and NAM solutions are not to be trusted in my opinion. I mean look at the charts at 69 hrs and tell me the low pressure area should be that broad and ridiculous looking with two centers along the coast. Just not going to happen. The GFS shifts this too far east way too early due to feedback issues.

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The position of this low at 54 hrs in the NE Gulf of Mexico is the same as it was with the December 26th storm. Hmm. I wonder if the model will have feedback problems with those thunderstorms developing down there?

the dec 26th storm did not have a storm kicker on its heels....my GUESS by looking at the h5 panel at 48hrs is that this will be EAST...not being NEGATIVE, just an educated guess based on logic.

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